Melting, sintering and wetting properties of ZnO–Bi_2O_3–B_2O_3 sealing glass

Glasses based on ZnO-Bi_2O_3-B_2O_3 system are expected to be a new kind of sealing glasses because of their low melting temperature and other properties.In order to reveal the effect of B_2O_3 on the rheological behavior of ZnO-Bi_2O_3-B_2O_3 system glass melt,the properties of viscosity,thermal expansion,fluxion property and wetting process between cylinder samples and stainless steel were investigated with the rotating crucible viscometer,dilato meter and high-temperature microscope.The structure of sintered glass samples was investigated with scanning electron microscope.The results show that the B_2O_3 content increasing in B_1-B_3 at the given temperature between 400 ℃ and 500 ℃ leads to the increasing of the sample viscosity.When the amount of B_2O_3 increases from 5.24%to 9.24%(mass fraction),the coefficients of thermal expansion of glass samples decrease smoothly from 10.94×10^(-6) to10.71×10^(-6) and 10.38×10^(-6) ℃^(-1) respectively.In the case of sealing temperature,its value increases from 453 ℃ to 494 ℃.ZnO-Bi_2O_3-B_2O_3 system low-melting glass powder sintering was with viscous liquid to participate,which could make the densification of glass sample more effective and more efficient.With the content of B_2O_3 increasing,the wetting angle between the glasses samples and stainless steel could also increase,and the resulting appropriate sealing temperature range is 460-490 ℃.

Structure of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glass

Bi2O3-ZnO-B2O3 system glass is a kind of lead-free low melting sealing glasses. The structure of Bi2O3-ZnO-B2O3 system low-melting sealing glass was investigated by DSC, FT-IR, XRD and SEM. The results show that with the increase of B2O3 content, the transition temperature Tg and softening temperature Tf of Bi2O3-ZnO-B2O3 system low-melting sealing glasses increase, which leads to the liquid phase precipitation temperature increasing and promotes the structure stability in the glass. With increasing the heat treatment temperature, a large number of liquid phases appear in samples and the sinter efficiency of the samples increases. The FT-IR spectra of the glasses show the presence of some bands that are assigned to vibrations of Bi--O bond from [BO3] pyramidal and [BiO6] octahedral units and B--O from [BO3] and [BO4] units. With the decrease of B203 content, the crystallization tendency of the glass increases. In glass samples Bl and B〉 crystallization starts at 460 ℃ and 540 ℃, respectively. Both of them precipitate Bi24B2O39 phases.

EFFECT OF SILANE ON THE SURFACE OF SEALING GLASS

This paper, through XPS and IR analyses on the surface of sealing glass, identifies that the surface treatment of sealing glass by silane is a chemical process. On the basis of the analyses, the authors suggest an ideal chemical bonding status between silane and glass surface.

Effect of SrO Content on Structure,Thermal Properties and Chemical Stability of Bi2O3-B2O3-ZnO-SrO Low-melting Glass for Si-Al Alloy Package

The 40Bi2O3-30B2O3-(30-x)ZnO-xSrO (x=0-15mol%,BBZSr) glass system was prepared by the conventional melt quenching method.The effect of SrO addition on structure,thermal properties,chemical stability and sealing performance of BBZSr glass were investigated thoroughly.The experimental results show that the total proportions of [BO3] group and [BO4] group decrease and the vibrations of [BiO3] group and [BiO6] group become weaker with the increase of SrO addition content,suggesting the glass network structure is strengthened owing to the SrO addition.Hence,both the thermal and chemical stability were significantly improved as the SrO content was increased.When the SrO content increased from 0 to 15mol%,the glass transition temperature and softening temperature slightly increased from 380 to 388 ℃ and from 392.7 to 402.2 ℃,respectively,meanwhile the coefficient of thermal expansion also increased from 10.49×10^-6 to 11.16×10^-6/℃ (30-300 ℃).The BBZSr glass with 15mol% SrO exhibited excellent comprehensive properties with low glass transition temperature(384.9 ℃),low softening temperature(400.3 ℃),high coefficient of thermal expansion (11.14×10^-6 ℃,30-300 ℃),good thermal and chemical stability.Besides,the glass had the good wetting behavior and sealing performance for Al-50%Si alloy.